1. Field
Embodiments relate to an accelerator pedal apparatus applied to vehicles and the like having a drive-by-wire system, and in particular, relates to an accelerator pedal apparatus capable of performing active control to generate reaction force (i.e., resistance force or press-back force) against tread force of a pedal arm for danger avoidance, danger notification, fuel consumption improvement, and the like.
2. Description of the Related Art
An accelerator pedal apparatus adopted to an electronically controlled throttle system (i.e., a drive-by-wire system) for an engine mounted on an automobile and the like includes a pedal arm (i.e., a pedal element) being rotatably supported to a housing (i.e., a pedal holding member) between a rest position and a maximum depression position while integrally having an accelerator pedal, an active control mechanism to control the accelerator pedal so as to be pressed-back against depression operation of a driver as being contacted to an upper end portion of the pedal arm, and the like. The active control mechanism disclosed in Japanese Patent Publication 2007-526177 includes a movable operation member (i.e., an operation push rod, a bowl-shaped yoke, and a ring-shaped magnet) linearly reciprocating in the approximate horizontal direction, a bowl-shaped coil bearing member fixed to the housing to exert electromagnetic drive force to the movable operation member, a coil wound around the coil bearing member, a spring urging the movable operation member so that the movable operation member (i.e., the operation push-rod thereof) is continuously contacted to the top end portion of the pedal arm, and the like.
Here, the active control mechanism adopts a solenoid type electromagnetic drive system as a drive source. Accordingly, the movable operation member contacted to the top end portion of the pedal arm is shaped elongated to reciprocate linearly in the approximate horizontal direction, so that the apparatus is upsized in the horizontal direction. Further, it is configured that the movable operation member transmits the electromagnetic drive force due to the solenoid type directly to the top end portion of the pedal arm. Therefore, variation in the electromagnetic drive force is directly transmitted to the pedal arm to cause a fear that stable active control operation cannot be performed. Further, the spring included in the active control mechanism is utilized for a return spring to return the pedal arm toward the rest position. Therefore, when the movable operation member is fixed to be non-movable in a state that the spring is compressed, there is a fear that the pedal arm cannot be returned completely to the rest position.
Further, another accelerator pedal apparatus includes a pedal arm (i.e., a pedal element) being rotatably supported to a housing between a rest position and a maximum depression position while integrally having an accelerator pedal, an active control mechanism to control the accelerator pedal so as to press back against depression operation of a driver as being contacted to an upper end portion of the pedal arm, and then, the active control mechanism includes a plunger element linearly reciprocating in the approximate horizontal direction, a torque motor exerting reciprocating drive force to the plunger element, a coil spring urging the plunger element to be continuously contacted to the top end portion of the pedal arm, and the like. An example of the above-noted accelerator pedal apparatus is disclosed in German Patent Publication DE 10-2004-025829A1.
Here, in the active control mechanism, the plunger element contacted to the top end portion of the pedal arm is shaped elongated to reciprocate linearly in the approximate horizontal direction, so that the apparatus is upsized in the horizontal direction. Further, it is configured that a rotation type torque motor is adopted as a drive source of the plunger element and the rotational drive force of the torque motor is converted into linear drive force of the plunger element via a pin to set arm length of the rotation torque to be approximately constant. Therefore, variation in the drive force (i.e., the torque) within the operational range of the torque motor is directly transmitted to the pedal arm via the plunger element to cause a fear that stable active control operation cannot be performed.
Further, similar to the abovementioned technology in the related art, the spring included in the active control mechanism is utilized for a return spring to return the pedal arm toward the rest position. Therefore, when the plunger element is fixed to be non-movable in a state that the spring is compressed, there is a fear that the pedal arm cannot be returned completely to the rest position.